JP4423989B2 - Thermoelectric generator for internal combustion engine - Google Patents

Description

  The present invention relates to a thermoelectric power generation apparatus for an internal combustion engine including a thermoelectric power generation element that converts thermal energy of exhaust gas into electric energy.

  A power generation technique using a thermoelectric power generation element that converts thermal energy into electrical energy is known. This thermoelectric power generation element uses the Seebeck effect that when a temperature difference is provided between both ends of a metal or a semiconductor, a potential difference is generated between the high temperature part and the low temperature part, and the power generation amount increases as the temperature difference increases. Become.

  FIG. 9 shows an example of the structure of the thermoelectric generator. As shown in FIG. 9, the thermoelectric generator has a substantially flat plate shape, and is mainly composed of n-type and p-type semiconductors. The high temperature side is a positive pole for an n-type semiconductor and a negative pole for a p-type semiconductor. And each of these semiconductors is connected in series with a plurality of electrodes and modularized to obtain a large electric power.

As a utilization form of such a thermoelectric power generation element, there is one described in Patent Document 1, for example. In the one described in Patent Document 1, a cylinder is provided in the middle of the exhaust passage of the internal combustion engine, and one surface of the thermoelectric generator is brought into contact with the outer peripheral surface of the cylinder, and the other surface of the thermoelectric generator is contacted. Is brought into contact with the cooling mechanism to convert the heat energy of the exhaust into electric energy.
JP 2002-325470 A

  By the way, in the thing of the said patent document 1, it is made to fix at least one contact surface with a bonding agent among the contact surfaces of a cylinder and a thermoelectric power generation element, and the contact surfaces of a thermoelectric power generation element and a cooling mechanism. Yes. For this reason, the following problems may occur.

  That is, when the thermal expansion coefficient of the fixing member to which the thermoelectric power generation element is fixed and the thermal expansion coefficient of the thermoelectric power generation element are different from each other, the deformation amounts due to temperature changes are different from each other. Therefore, thermal stress acts on the thermoelectric power generation element, which may cause damage to the element.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a thermoelectric power generation apparatus for an internal combustion engine that can suppress damage to thermoelectric power generation elements.

In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, there is provided a thermoelectric power generation element that converts thermal energy of exhaust gas discharged into an exhaust passage of an internal combustion engine into electric energy, a part of the exhaust passage and one of the thermoelectric power generation elements. In a thermoelectric generator for an internal combustion engine, comprising a high temperature member in contact with a surface and a low temperature member in contact with the other surface of the thermoelectric generator, the thermoelectric generator is arranged concentrically in the exhaust passage, and the thermoelectric generator is disposed in the exhaust passage A holding member that holds its position by pressing against the surface, and is disposed between the holding member and the low temperature member, and the thermoelectric power generation element is thermally expanded with respect to both the high temperature member and the low temperature member. with an elastic member of the thermoelectric power generating element to a state of being biased between the low temperature member and the high temperature member is provided so as to be slidable in accordance with the deformation amount of the high temperature section The inside are those exhaust purification catalyst is provided, the number of wall carrier in the same exhaust gas purifying catalyst is formed therein by being extruded is a metal carrier are integrated The gist.

  According to this configuration, the thermoelectric generator and the high temperature member are slidably provided. Therefore, when the deformation amounts are different due to the difference in thermal expansion coefficient between the thermoelectric generator and the high temperature member, the members move relative to each other, and the stress acting on the thermoelectric generator is reduced. The Therefore, it is possible to suitably suppress the thermal stress generated due to the difference in thermal expansion coefficient between the thermoelectric power generation element and the high temperature member from acting on the thermoelectric power generation element. Similarly, since the thermoelectric power generation element and the low temperature member are also slidably provided, it is preferable that the thermal stress generated due to the difference in thermal expansion coefficient between the thermoelectric power generation element and the low temperature member acts on the thermoelectric power generation element. Can be suppressed. Thus, according to the said structure, damage to a thermoelectric power generation element can be suppressed now.

  In addition, the thermoelectric power generation element is slidably provided with respect to both the high temperature member and the low temperature member, and the high temperature member, the low temperature member, and the thermoelectric power generation element are in direct contact with each other. The amount of power generation according to the temperature difference can be suitably ensured.

In addition, since the thermoelectric power generation element is not fixed to the high temperature member or the low temperature member and the arrangement position of the thermoelectric power generation element is maintained, the thermoelectric power generation element is reliably slid against both the high temperature member and the low temperature member. Can be made movable.

In holding the thermoelectric power generation element by such a pressing force, it is possible to adopt a mode in which the thermoelectric power generation element, the high temperature member, and the low temperature member are integrally fixed using a fastening member such as a band.
On the other hand, an exhaust purification catalyst is provided inside the high temperature member. Since the temperature of the exhaust purification catalyst is raised by the heat of chemical reaction, the temperature becomes higher than the members constituting the exhaust passage. Therefore, according to the said structure, the temperature of a high temperature member can further be raised and the electric power generation amount of a thermoelectric power generation element can be increased now. Therefore, according to the configuration of the first aspect, even when the high temperature member is deformed due to thermal expansion or the like, damage to the thermoelectric power generation element can be suppressed. Even if such a configuration is adopted, damage to the thermoelectric power generation element can be suppressed.
Since the exhaust purification catalyst and the thermoelectric generator are integrated, the entire exhaust system of the internal combustion engine is compact compared to the case where the exhaust purification catalyst and the thermoelectric generator are provided as separate devices in the exhaust passage. Can be configured.
Further, when the engine operating state is in a high rotation and high load state, the exhaust temperature rises and the exhaust purification catalyst is likely to be deteriorated at a high temperature. Therefore, such high temperature degradation can be suitably suppressed.
Incidentally, the exhaust purification catalyst carrier is an extruded metal carrier. Examples of the carrier include a ceramic carrier and a metal carrier. In this configuration, a metal carrier is particularly adopted. In such a metal carrier, the heat of chemical reaction and exhaust heat generated on the carrier is easily transferred, so that the temperature rise rate is faster than that of the ceramic carrier, and the temperature itself is higher. Therefore, according to the above configuration, the temperature of the surface on the high temperature side of the thermoelectric generator can be raised more rapidly, and the temperature of the surface on the high temperature side can be increased.
Examples of such a metal carrier include a carrier obtained by laminating a large number of metal thin plates, and a carrier obtained by rolling a metal thin plate into a spiral shape. However, the carrier formed of these thin metal plates has low rigidity and tends to be largely deformed by external force. Therefore, these carriers are deformed by the pressing force as described above, and may be damaged in some cases. Therefore, in the above configuration, an extruded metal carrier is employed. Since this extruded carrier has a large number of wall surfaces formed inside it, it is more rigid than each carrier composed of a thin metal plate as described above, and is less deformed by external force. There are features. Therefore, the deformation of the carrier can be suitably suppressed when the power generation amount is increased due to the increase of the pressing force.

Invention according to claim 2, in the thermoelectric power generating apparatus for an internal combustion engine according to claim 1, a pedestal the one surface is in contact with the outer peripheral surface of the hot member constituting a part of the high temperature member The gist is to be provided.

  By increasing the adhesion between the thermoelectric element and the high temperature member, or the adhesion between the thermoelectric element and the low temperature member, the amount of heat transferred from the high temperature member to the thermoelectric element or the heat transfer from the thermoelectric element to the low temperature member Therefore, the amount of power generated by the thermoelectric generator can be increased. Here, if the pressing force between the thermoelectric power generation element and the high temperature member is increased in order to improve the adhesion, the high temperature member may be deformed. Therefore, in the above configuration, a pedestal is provided on the outer peripheral surface of the high temperature member, and one surface of the thermoelectric power generation element is brought into contact with the pedestal. By providing such a pedestal, the rigidity of the high temperature member including the pedestal is increased, and even when the pressing force is increased as described above, the deformation of the high temperature member can be suppressed. In addition, the arrangement | positioning aspect of forming the said base integrally with a high temperature member, the arrangement | positioning aspect of forming as a member different from a high temperature member, and attaching so that it may contact the outer peripheral surface of a high temperature member, etc. are employable.

According to a third aspect of the present invention, in the thermoelectric power generator for an internal combustion engine according to the second aspect, the surface of the pedestal that contacts the one surface is formed in a shape along the one surface. Is the gist.

According to this configuration, it is possible to reliably ensure the adhesion between the one surface of the thermoelectric power generation element and the pedestal constituting a part of the high temperature member. Here, the thermoelectric generator is often formed in a substantially flat plate shape. Therefore, as described in the fourth aspect of the present invention, by forming the pedestal in a polygonal column shape, the outer peripheral surface of the pedestal and one surface of the thermoelectric power generation element can be reliably brought into close contact with each other.

The gist of a fifth aspect of the present invention is the thermoelectric power generator for an internal combustion engine according to any of the first to fourth aspects, wherein the high temperature member is formed of austenitic stainless steel.

  As the material of the exhaust passage, stainless steel having excellent corrosion resistance may be used. Among these stainless steels, austenitic stainless steel (for example, SUS303, SUS304, etc.) has a characteristic that its coefficient of thermal expansion is larger than that of other stainless steels. Therefore, when the high temperature member is formed using this austenitic stainless steel, the amount of thermal expansion becomes large. Therefore, when the thermoelectric generator is directly provided on the high-temperature member, the thermal expansion of the high-temperature member increases the adhesion between the high-temperature member and the thermoelectric generator, and the amount of heat transfer from the high-temperature member to the thermoelectric generator is increased. The power generation amount of the thermoelectric power generation element can be further increased. Even when the pedestal as described above is provided, the pedestal is elastically deformed due to the thermal expansion of the high temperature member, and the adhesion between the pedestal and the thermoelectric power generation element is increased. The amount can be further increased.

The invention described in claim 6 is the thermoelectric power generating apparatus for an internal combustion engine according to claim 1, wherein the low temperature member is a cooling mechanism cooling refrigerant flows therein, within the cooling mechanism The gist is that the flow direction of the cooling medium is set in the direction from the top to the bottom of the cooling mechanism.

  According to this configuration, since a drop occurs between the upstream side and the downstream side of the cooling medium introduced into the cooling mechanism, the cooling medium can be efficiently circulated in the cooling mechanism, and the low temperature of the thermoelectric generator element can be reduced. The side cooling can be suitably performed.

According to a seventh aspect of the present invention, the flow direction of the cooling medium is set to a forward direction with respect to the flow direction of the exhaust gas in addition to the direction from the upper side to the lower side of the cooling mechanism. By adopting such a configuration, the cooling medium flows from the upper exhaust upstream side of the cooling mechanism toward the lower exhaust downstream side, so that the entire cooling mechanism can be suitably cooled.

The invention according to claim 8 is the thermoelectric power generator for an internal combustion engine according to any one of claims 1 to 7 , wherein at least one of the one surface and the other surface is coated with an amorphous carbon film. This is the gist.

Since the amorphous carbon film, so-called DLC (Diamond Like Carbon) film, has a small coefficient of friction, according to the above configuration, the sliding resistance between the thermoelectric power generating element and the thermoelectric power generating element is reduced. Damage to the element can be sufficiently suppressed. Further, since the amorphous carbon film has high electrical insulation, it is possible to ensure insulation between the electrodes on the high temperature side of the thermoelectric power generation element or insulation between the electrodes on the low temperature side. Moreover, since the amorphous carbon film has high thermal conductivity, it is possible to reliably secure the amount of power generation according to the temperature difference between the high temperature member and the low temperature member. Furthermore, since the amorphous carbon film is excellent in heat resistance, wear resistance and the like, the effects of the inventions described in claims 1 to 7 can be maintained for a long period of time.

Hereinafter, an embodiment embodying a thermoelectric generator for an internal combustion engine according to the present invention will be described with reference to FIGS.
FIG. 1 shows a schematic configuration of an exhaust system 12 of a vehicle 1 to which a thermoelectric generator 20 for an internal combustion engine according to this embodiment is applied.

  As shown in FIG. 1, an exhaust manifold 13, a thermoelectric generator 20, a silencer 16, and the like are disposed in the exhaust passage 17 constituting the exhaust system 12 in order from the upstream side in the exhaust flow direction. . In the exhaust system 12 configured as described above, the exhaust discharged from the internal combustion engine 11 passes through the exhaust manifold 13, the thermoelectric generator 20, and the silencer 16 and is discharged to the outside.

Next, the thermoelectric generator 20 will be described with reference to FIGS.
FIG. 2 shows a perspective view of the thermoelectric generator 20. FIG. 3 shows a partial cross-sectional view of the thermoelectric generator 20. As shown in FIG. 3, the thermoelectric generator 20 includes an exhaust purification catalyst 30, a thermoelectric generator stack 40, and the like.

  The exhaust purification catalyst 30 includes a cylindrical carrier 31 and an outer cylinder 32 that accommodates the carrier 31. The carrier 31 carries a catalyst for purifying exhaust components such as HC (hydrocarbon), CO (carbon monoxide), NOx (nitrogen oxide), etc. by reaching a predetermined activation temperature.

  The outer cylinder 32 is made of stainless steel, which is a material having high thermal conductivity and corrosion resistance. In particular, in this embodiment, austenitic stainless steel (for example, SUS303, SUS304) having a larger coefficient of thermal expansion than other stainless steels. Etc.) are used. Both ends of the outer cylinder 32 are opened, an upstream flange 33 to which the exhaust manifold 13 is connected is provided at one end, and a downstream flange 34 to which the exhaust passage 17 is connected at the other end. It has been. Thus, the outer cylinder 32 forms a part of the exhaust passage 17 and constitutes the high temperature member. The outer cylinder 32 is press-fitted into the pedestal 35. The pedestal 35 is formed of a material having high thermal conductivity and high heat resistance (for example, stainless steel, aluminum alloy, copper, etc.), and heat of the outer cylinder 32 is easily transmitted. That is, the pedestal 35 constitutes a part of the high temperature member.

  The thermoelectric power generation stack 40 includes a plurality of thermoelectric power generation elements 41, a cooling mechanism 42, and the like. Each thermoelectric power generation element 41 has the same structure as that shown in FIG. However, in this embodiment, the electrodes provided on both surfaces of the thermoelectric power generation element 41 are covered with an amorphous carbon film (DLC film) 41a. The amorphous carbon film 41a has characteristics such as a small friction coefficient and excellent characteristics such as electrical insulation, thermal conductivity, heat resistance, and wear resistance.

  A plurality of (four in this embodiment) thermoelectric generator elements 41 are provided in the outer peripheral surface of the pedestal 35 in the axial direction of the exhaust purification catalyst 30, that is, in the exhaust flow direction, and are in contact with the outer peripheral surface of the pedestal 35. (Hereinafter referred to as surface H) is in the thermoelectric power generation element 41 and becomes a surface on the high temperature side.

  The cooling mechanism 42 is provided in the thermoelectric power generation element 41 on the surface opposite to the surface facing the outer peripheral surface of the pedestal 35. The cooling mechanism 42 includes an introduction pipe 43, a first collecting part 44, a distribution pipe 45, a cooling part 46, and a second collecting part, which are provided in order from the upstream side in the flow direction of the cooling water that is a cooling medium that circulates inside the cooling mechanism 42. 47, a discharge pipe 48, and the like. This cooling mechanism constitutes the low temperature member.

  The first collecting portion 44 and the second collecting portion 47 are each configured as an annular pipe provided outward from the circumferential surface of the outer cylinder 32, and the first collecting portion is located upstream in the exhaust flow direction. 44, the 2nd gathering part 47 is provided in the downstream. Each of these collective portions is connected by a plurality of distribution pipes 45 extending in the axial direction of the exhaust purification catalyst 30.

  A cooling part 46 for cooling the thermoelectric power generation element 41 is provided in the middle of each distribution pipe 45, and a surface (hereinafter referred to as a surface C) on the thermoelectric power generation element 41 that contacts the cooling part 46 is a low temperature of the same element. Become the side face. Cooling water is introduced into the internal space of the cooling unit 46 through the distribution pipe 45. The cooling unit 46 is provided individually corresponding to each thermoelectric power generation element 41.

  The introduction pipe 43 is connected above the first collection section 44, and cooling water is introduced into the first collection section 44 via the introduction pipe 43. Further, the discharge pipe 48 is connected to the lower side of the second collecting portion 47, and the cooling water of the second collecting portion is introduced into a separately provided cooling system via the discharge pipe 48. As described above, the introduction pipe 43 is provided above the first collection portion 44 provided on the exhaust upstream side, and the discharge pipe 48 is provided below the second collection portion 47 provided on the exhaust downstream side of the first collection portion 44. Is provided. Thus, the flow direction of the cooling water in the cooling mechanism 42 is set to a direction from the upper side to the lower side of the cooling mechanism 42, and further set to be forward with respect to the flow direction of the exhaust gas. Yes.

Next, the AA cross section in FIG. 3 is shown in FIG. As shown in FIG. 4, the carrier 31 is inserted into the outer cylinder 32, and the outer cylinder 32 is inserted into the pedestal 35. This carrier 31 is an extruded metal carrier. More specifically, it is a honeycomb structure having a large number of through holes in its full length direction, and the wall surface constituting the through holes is formed of sintered metal. Incidentally, in this embodiment as the sintered metal, the use of the iron plus chromium and aluminum alloys, it is also possible to use other as long as it is a metal having excellent heat resistance.

The pedestal 35 is formed in a polygonal column shape extending in the insertion direction of the outer cylinder 32, specifically, an octagonal column shape. Further, a hole for inserting the outer cylinder is formed in the inside.
A plurality of thermoelectric power generation elements 41 are in contact with the outer peripheral surface of the pedestal 35. In the present embodiment, eight thermoelectric power generation elements 41 are arranged in the radial direction of the pedestal 35 and four in the axial direction of the pedestal 35, and a total of 32 (8 × Four) thermoelectric generators 41 are in contact. Each thermoelectric power generation element 41 is arranged at an equal angle (45 °) in the circumferential direction of the pedestal 35.

The above-described cooling unit 46 is in contact with the surface C of each thermoelectric generation element 41. As shown in FIG. 4, a plurality of heat radiating plates 49 are formed inside each cooling unit 46.
A disc spring 50 and a spring retainer 51 are disposed on the surface of each cooling unit 46 opposite to the surface (surface C) with which the thermoelectric generator 41 is in contact. Each cooling unit 46 in contact with each thermoelectric power generation element 41 is fixed by a band 52 via a disc spring 50 and a spring presser 51. Therefore, the cooling part 46, the thermoelectric power generation element 41, the pedestal 35, and the outer cylinder 32 are integrally fixed by a fastening member such as the band 52. Then, the thermoelectric power generation element 41 is pressed by the cooling unit 46 and the pedestal 35 and the arrangement position of the thermoelectric power generation element 41 is held, so that the thermoelectric power generation element 41 is one of the cooling unit 46 and the high temperature member of the cooling mechanism 42. Each slidable state is held on a pedestal 35 constituting the part. In the present embodiment, the band 52 is made of metal, but other materials may be used. Further, instead of the disc spring 50, another elastic member may be used.

  In the thermoelectric generator 20 according to the present embodiment configured as described above, the thermoelectric generator 41 is held by the thermoelectric generator 41 being pressed by the pedestal 35 and the cooling unit 46. Accordingly, the thermoelectric power generation element 41 is not completely fixed to the pedestal 35 and the cooling unit 46, and the arrangement position thereof is maintained, and the thermoelectric power generation element 41 is slidable with respect to both the pedestal 35 and the cooling unit 46. Arranged in a manner. Therefore, when the deformation amount is different due to the difference in thermal expansion coefficient between the thermoelectric power generation element 41 and the pedestal 35, the mutual members (thermoelectric power generation element 41 and pedestal 35) come to move relative to each other, The stress acting on the thermoelectric generator 41 is reduced. Therefore, the thermal stress generated due to the difference in thermal expansion coefficient between the thermoelectric power generation element 41 and the pedestal 35 is suppressed from acting on the thermoelectric power generation element 41. Similarly, since the thermoelectric generation element 41 and the cooling unit 46 are also slidably arranged, the thermal stress generated due to the difference in thermal expansion coefficient between the thermoelectric generation element 41 and the cooling unit 46 is generated by the thermoelectric generation. Acting on the element 41 is suppressed. Therefore, damage to the thermoelectric generator 41 is suppressed.

  Further, the thermoelectric power generation element 41 is slidably provided with respect to both the pedestal 35 and the cooling unit 46, and the pedestal 35 and the thermoelectric power generation element 41, and the cooling unit 46 and the thermoelectric power generation element 41 are in direct contact with each other. Therefore, the power generation amount according to the temperature difference between the pedestal 35 and the cooling unit 46 is ensured.

  Note that the band 52 is used to integrally fix the thermoelectric power generation element 41, the pedestal 35, and the cooling unit 46. Therefore, the arrangement position of the thermoelectric generator 41 is held while being pressed with a simple configuration.

Moreover, since the thermoelectric generation element 41 is not completely fixed, the thermoelectric generation element 41 can be easily replaced.
Here, by increasing the adhesion between the thermoelectric power generation element and the high temperature member, or the adhesion between the thermoelectric power generation element and the low temperature member, the amount of heat transfer from the high temperature member to the thermoelectric generation element, or from the thermoelectric power generation element to the low temperature member. Therefore, the amount of heat generated by the thermoelectric generator can be increased. However, if the pressing force between the thermoelectric generator and the high temperature member is increased in order to improve such adhesion, the high temperature member may be deformed. Therefore, in the present embodiment, a pedestal 35 is provided on the outer peripheral surface of the outer cylinder 32 that is a high-temperature member, and one surface (surface H) of the thermoelectric power generation element 41 is in contact with the pedestal 35. By providing such a pedestal 35, the rigidity of the high temperature member including the pedestal 35 is increased, and even when the pressing force is increased as described above, deformation of the high temperature member (outer cylinder 32) is suppressed.

  Moreover, since the thermoelectric power generation element 41 is formed in a substantially flat plate shape, the shape of the pedestal 35 is a polygonal column shape. That is, the surface of the pedestal 35 that contacts the surface H of the thermoelectric generator 41 is formed in a shape along the surface H. Therefore, the adhesion between the surface H of the thermoelectric generator 41 and the pedestal 35 is reliably ensured.

  The outer cylinder 32 is formed of austenitic stainless steel. Therefore, the amount of thermal expansion of the outer cylinder 32 is larger than when other stainless steel is used, and the pedestal 35 is biased toward the thermoelectric power generation element 41 by the expansion of the outer cylinder 32 in the radial direction. The Thereby, the adhesiveness between the pedestal 35 and the thermoelectric power generation element 41 is enhanced, and the amount of heat transfer from the pedestal 35 to the thermoelectric power generation element 41 is increased. As a result, the power generation amount of the thermoelectric power generation element 41 is further increased.

An exhaust purification catalyst 30 is provided inside the outer cylinder 32. Since the temperature of the exhaust purification catalyst 30 is increased by the heat of chemical reaction during exhaust purification, the temperature is higher than that of the exhaust manifold 13 and the exhaust passage 17. Therefore, the temperature of the outer cylinder 32 is further increased as compared with the case where the exhaust purification catalyst 30 is not provided. Therefore, the temperature of the pedestal 35 in contact with the outer peripheral surface of the outer cylinder 32 also becomes higher, and the power generation amount of the thermoelectric power generation element 41 is further increased. Note that, when the temperature of the pedestal 35 is further increased, the amount of deformation due to thermal expansion also increases. However, in this embodiment, even if the high temperature member is deformed due to thermal expansion or the like, damage to the thermoelectric power generation element is suppressed. Therefore, even if such a configuration that further increases the temperature of the pedestal 35 is employed, damage to the thermoelectric power generation element 41 is suppressed . Also, since the exhaust purification catalyst 30 and the thermoelectric generator 20 is integrated, as compared with the case of providing in the exhaust passage 17 and the exhaust gas purifying catalyst 30 and the thermoelectric generator 20 as separate devices, respectively, an internal combustion engine The entire exhaust system is compact.

Further, when the engine operating state is in a high rotation and high load state, the exhaust temperature rises and the exhaust purification catalyst 30 is likely to deteriorate at a high temperature. However, in this embodiment, the amount of heat of the exhaust purification catalyst 30 depends on the thermoelectric power generation element. Since it is consumed by 41, such high temperature degradation is also suppressed .
Further, the carrier 31 of the exhaust purification catalyst 30 is a metal carrier. In such a metal carrier, the heat of chemical reaction and the heat of exhaust generated on the carrier is easily transferred, so that the temperature rise rate is faster than the ceramic carrier and the temperature itself is higher. Therefore, according to this embodiment, the temperature of the high temperature side surface (surface H) of the thermoelectric generator 41 can be raised more quickly, and the temperature of the high temperature side surface can be further increased. Therefore, the power generation amount of the thermoelectric power generation element 41 can be further increased. In addition, such metal carriers include a carrier in which a large number of thin metal plates are laminated and a carrier obtained by rolling a thin metal plate into a spiral shape. However, a carrier formed of these thin metal plates has low rigidity and an external force. There is a tendency that the amount of deformation due to. Therefore, these carriers are deformed by the pressing force applied through the outer cylinder 32 and may be damaged in some cases. Therefore, in this embodiment, an extruded metal carrier is used. Since this extruded carrier has a large number of wall surfaces formed therein, it is characterized by higher rigidity and less deformation due to external force than a carrier made of a thin metal plate. Therefore, deformation of the carrier is suppressed when the amount of power generation is increased due to an increase in the pressing force.

  Further, a cooling mechanism 42 through which cooling water flows is provided on the low temperature side of the thermoelectric power generation element 41 so as to sufficiently cool the low temperature side. The cooling mechanism 42 is set in a direction from above to below. Therefore, a drop occurs between the upstream side and the downstream side of the cooling water introduced into the cooling mechanism 42, and the cooling water is efficiently distributed in the cooling mechanism 42. Further, the flow direction of the cooling water is set to the forward direction with respect to the flow direction of the exhaust gas. Therefore, the cooling water flows from the upper exhaust upstream side of the cooling mechanism 42 toward the lower exhaust downstream side, and the entire cooling mechanism 42 is sufficiently cooled.

  Further, the high temperature surface (surface H) and the low temperature surface (surface C) of the thermoelectric power generation element 41 are covered with an amorphous carbon film 41a. Since this amorphous carbon film 41a, so-called DLC (Diamond Like Carbon) film, has a small coefficient of friction, the sliding resistance between the thermoelectric power generation element 41 and the members (the pedestal 35 and the cooling unit 46) that are in contact with the thermoelectric power generation element 41. Becomes smaller. Therefore, each of the pedestal 35 and the cooling unit 46 and the thermoelectric power generation element 41 are easily slid, and thus damage to the thermoelectric power generation element 41 is sufficiently suppressed. In addition, since the amorphous carbon film 41a has high electrical insulation, it is possible to ensure insulation between the electrodes on the high temperature side of the thermoelectric generator 41 or insulation between the electrodes on the low temperature side. Moreover, since the amorphous carbon film 41a has high thermal conductivity, a power generation amount according to the temperature difference between the high temperature member and the low temperature member is reliably ensured. Further, since the amorphous carbon film 41a is excellent in heat resistance, wear resistance and the like, the above-described effects are maintained over a long period of time.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The thermoelectric generator 41 is provided so as to be slidable with respect to both the high temperature member (base 35) and the low temperature member (cooling unit 46). Therefore, it becomes possible to suppress damage to the thermoelectric power generation element 41 due to the difference in thermal expansion coefficient between the high temperature member and the low temperature member and the thermoelectric power generation element 41.

  Further, the thermoelectric power generation element 41 is slidably provided on both the high temperature member and the low temperature member, and the high temperature member and the thermoelectric power generation element, and the low temperature member and the thermoelectric power generation element are in direct contact with each other, A power generation amount corresponding to the temperature difference between the high temperature member and the low temperature member can be suitably secured.

  (2) The thermoelectric power generation element 41 is pressed by a high temperature member and a low temperature member so that the arrangement position thereof is maintained. Therefore, the thermoelectric power generation element 41 is not completely fixed to the high temperature member or the low temperature member, and the arrangement position of the thermoelectric power generation element 41 is maintained, and the high temperature member, the low temperature member, and the thermoelectric power generation element 41 are slid reliably. Can be possible.

(3) Since the thermoelectric power generation element 41 is not completely fixed, the thermoelectric power generation element 41 can be easily replaced.
(4) When holding the thermoelectric power generation element 41 by such a pressing force, the thermoelectric power generation element 41, the high temperature member, and the low temperature member are integrally fixed using a band 52. Therefore, the arrangement position can be held while pressing the thermoelectric generator 41 with a simple configuration.

  (5) A pedestal 35 constituting a part of the high temperature member is provided on the outer peripheral surface of the outer cylinder 32 constituting a part of the exhaust passage. Therefore, the deformation of the outer cylinder 32 can be suppressed while increasing the power generation amount of the thermoelectric power generation element 41.

  (6) The surface of the pedestal 35 that is in contact with one surface (surface H) of the thermoelectric generator 41 is formed in a shape along this one surface. Specifically, the pedestal 35 is formed in a polygonal column shape. Therefore, it becomes possible to reliably ensure the adhesion between the one surface of the thermoelectric power generation element 41 and the pedestal 35 constituting a part of the high temperature member.

  (7) The outer cylinder 32 is formed of austenitic stainless steel. Therefore, the adhesion between the pedestal 35 and the thermoelectric power generation element 41 is further increased, and the power generation amount of the thermoelectric power generation element 41 can be further increased.

  (8) The exhaust purification catalyst 30 is provided inside the outer cylinder 32. Therefore, the temperature of the pedestal 35 can be further increased, and the amount of power generated by the thermoelectric power generation element 41 can be increased. In addition, according to the said embodiment, even if it is a case where high temperature members, such as the base 35, deform | transform by thermal expansion etc., since damage to the thermoelectric power generation element 41 can be suppressed, the temperature of the base 35 is further increased in this way. Even if it is the structure which raises, the damage of the thermoelectric power generation element 41 can be suppressed.

(9) Since the exhaust purification catalyst 30 and the thermoelectric generator 20 are configured integrally, the entire exhaust system of the internal combustion engine can be configured compactly.
(10) When the engine operating state is in a high rotation and high load state, the exhaust temperature rises and the exhaust purification catalyst 30 is likely to deteriorate at a high temperature. According to the above embodiment, such a high temperature deterioration is also suitable. Can be suppressed.

  (11) The carrier 31 of the exhaust purification catalyst 30 is an extruded metal carrier. Therefore, the temperature of the high temperature side surface of the thermoelectric power generation element 41 can be raised more quickly, and the temperature of the high temperature side surface can be further increased, thereby further increasing the power generation amount of the thermoelectric power generation element 41. To be able to.

Further, when the power generation amount is increased by increasing the pressing force on the thermoelectric power generation element 41, the deformation of the carrier 31 can be suitably suppressed.
(12) The flow direction of the cooling water in the cooling mechanism 42 is set to a direction from the upper side to the lower side of the cooling mechanism 42. Therefore, the cooling water can be efficiently circulated in the cooling mechanism 42, and cooling of the thermoelectric power generation element 41 on the low temperature side can be suitably performed.

Further, the flow direction of the cooling water is set to the forward direction with respect to the flow direction of the exhaust gas. Accordingly, the entire cooling mechanism 42 can be suitably cooled.
(13) Both surfaces of the thermoelectric generator 41 are covered with the amorphous carbon film 41a. Therefore, the sliding resistance between the member in contact with the thermoelectric power generation element 41 and the thermoelectric power generation element 41 is reduced, and damage to the thermoelectric power generation element 41 can be sufficiently suppressed. Further, it is possible to ensure insulation between the electrodes on the high temperature side of the thermoelectric generator 41 or insulation between the electrodes on the low temperature side. In addition, the amount of power generation according to the temperature difference between the high temperature member and the low temperature member can be ensured. Furthermore, the above-described effects can be maintained over a long period of time.

In addition, the said embodiment can also be changed and implemented as follows.
In the above embodiment, the cooling unit 46, the thermoelectric power generation element 41, and the pedestal 35 are integrally fixed using the band 52. However, the thermoelectric power generation element 41 is pressed in the manner illustrated in FIG. And the arrangement | positioning position can also be hold | maintained.

  That is, a carrier 31 ′ having a substantially polygonal cross section perpendicular to the exhaust flow direction is prepared, and the carrier 31 ′ is inserted into an outer cylinder 32 ′ having a polygonal column shape. Further, a cooling mechanism 42 ′ is prepared in which the cooling part 46 is integrally formed in the circumferential direction of the outer cylinder 32 ′ and the exhaust flow direction. Then, the thermoelectric generator 41 is temporarily fixed to the inner peripheral surface of the cooling mechanism 42 ', and the thermoelectric generator 41 and the cooling mechanism 42' are press-fitted into the outer peripheral surface of the outer cylinder 32 '. In this way, the low temperature member and the thermoelectric power generation element are temporarily fixed, and the low temperature member and the thermoelectric power generation element are press-fitted into the outer peripheral surface of the high temperature member, so that the thermoelectric power generation element is pressed between the high temperature member and the low temperature member. In this embodiment, the band 52 can be omitted. Therefore, the thermoelectric power generation element 41 is pressed by the high temperature member and the low temperature member with a simpler structure, and the arrangement position thereof is maintained.

  In addition, in order to press-fit the thermoelectric generation element between the high temperature member and the low temperature member, the high temperature member and the thermoelectric generation element are temporarily fixed, and the high temperature member and the thermoelectric generation element are pressed into the inner peripheral surface of the low temperature member. You may do it. Further, the thermoelectric power generation element can be brought into the press-fitted state by pressing the thermoelectric power generation element between the high temperature member and the low temperature member.

  As illustrated in FIG. 6, the pedestal 35 in the above embodiment can be omitted. In this case, by using the carrier 31 ′ and the outer cylinder 32 ′ illustrated in FIG. 5, the one surface (surface H) of the thermoelectric generator 41 is directly on the outer peripheral surface of the outer cylinder 32 ′. In addition to being in contact, the entire surface H comes into contact with the outer cylinder 32 ', so that the amount of heat of the carrier can be suitably transmitted to the thermoelectric generator.

  Incidentally, in FIG. 5, the case where the thermoelectric power generation element is press-fitted between the high temperature member and the low temperature member and the pedestal 35 is omitted is illustrated. However, as illustrated in FIG. Similarly, when the pedestal 35 is provided, the thermoelectric power generation element 41 may be press-fitted on the outer peripheral surface side of the pedestal 35.

  -The pedestal 35 in the above embodiment may be formed of austenitic stainless steel. In this case, since the thermal expansion amount of the pedestal 35 increases and the adhesion between the thermoelectric power generation element 41 and the pedestal 35 is improved, the heat transfer amount from the pedestal 35 to the thermoelectric power generation element 41 is increased, and the amount of power generation is increased. Can be further increased.

The pedestal 35 and the outer cylinder 32 may be integrally formed, and the exhaust purification catalyst 30 may be inserted into the integrally formed pedestal.
As described above, the carrier 31 is preferably an extruded metal carrier, but may be a ceramic carrier or a metal carrier composed of a thin metal plate or the like.

The exhaust purification catalyst in the above embodiment and its modification may be any one that generates heat when purifying exhaust components.
The carrier in the outer cylinder 32 or the outer cylinder 32 ′, in other words, the exhaust purification catalyst can be omitted. That is, the present invention can be similarly applied even when the thermoelectric generator 41 is provided on the outer peripheral surface of the exhaust pipe constituting the exhaust system.

  Although both surfaces of the thermoelectric power generation element 41 are covered with the amorphous carbon film 41a, the film used for this coating has a small friction coefficient, electrical insulation, thermal conductivity, heat resistance, and wear resistance. It is sufficient if it is excellent. Further, one surface (for example, the surface H) of the thermoelectric power generation element 41 may be covered with the amorphous carbon film 41a, and the other one surface (for example, the surface C) may be covered with a different film.

-The number of the thermoelectric power generation elements 41 can be changed as appropriate.
In the embodiment described above, the flow direction of the cooling water in the cooling mechanism 42 is also set to be forward with respect to the flow direction of the exhaust gas. In this respect, the flow direction of the cooling water may be set to be at least a direction from the upper side to the lower side of the cooling mechanism 42. Even in this case, since a drop occurs between the upstream side and the downstream side of the cooling water introduced into the cooling mechanism 42, the cooling water can be efficiently circulated in the cooling mechanism 42. Cooling on the low temperature side of the element 41 can be suitably performed.

  In the above embodiment, the cooling water is used as the cooling medium of the cooling mechanism 42, but other cooling media can be used. In short, any medium capable of cooling the cooling mechanism 42 may be used.

The cooling mechanism 42 is a so-called water-cooling cooling mechanism, but may be an air-cooling cooling mechanism having heat radiation fins, for example.
The disc spring 50 and the spring retainer 51 may be omitted, and the cooling unit 46 and the like may be directly tightened with the band 52.

  As illustrated in FIG. 8, the thermoelectric generator 20 may be provided directly below the exhaust manifold 13. In this case, it is possible to contribute to flattening the under floor of the vehicle 1. Therefore, for example, the floor surface in the vehicle compartment can be formed more flat, and the comfort in the cabin can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the structure of the exhaust system of the vehicle to which this is applied about one Embodiment of the thermoelectric generator of the internal combustion engine concerning this invention. The perspective view which shows the structure of the thermoelectric power generating apparatus concerning the embodiment. The fragmentary sectional view which shows the structure of the thermoelectric power generating apparatus concerning the embodiment. AA sectional drawing of FIG. The schematic diagram which shows the structure of the cross section orthogonal to the flow direction of exhaust_gas | exhaustion in the thermoelectric power generation apparatus in the modification of the embodiment. The schematic diagram which shows the structure of the cross section orthogonal to the flow direction of exhaust_gas | exhaustion in the thermoelectric power generation apparatus in the modification of the embodiment. The schematic diagram which shows the structure of the cross section orthogonal to the flow direction of exhaust_gas | exhaustion in the thermoelectric power generation apparatus in the modification of the embodiment. Schematic which shows the arrangement position of the thermoelectric power generator in the modification of the embodiment. Schematic which shows the structure of a thermoelectric power generation element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 11 ... Internal combustion engine, 12 ... Exhaust system, 13 ... Exhaust manifold, 16 ... Silencer, 17 ... Exhaust passage, 20 ... Thermoelectric generator, 30 ... Exhaust purification catalyst, 31, 31 '... Carrier, 32, 32 '... outer cylinder, 33 ... upstream flange, 34 ... downstream flange, 35 ... pedestal, 40 ... thermoelectric power generation stack, 41 ... thermoelectric power generation element, 41a ... amorphous carbon film, 42 ... cooling mechanism, 43 ... introduction Pipes 44... First collecting part 45. Distribution pipe 46. Cooling part 47. Second collecting part 48. Discharge pipe 49. Radiating plate 50 .. Disc spring 52.

Claims (8)

A thermoelectric power generation element that converts thermal energy of exhaust discharged into an exhaust passage of an internal combustion engine into electrical energy; a high-temperature member that constitutes a part of the exhaust path and that contacts one surface of the thermoelectric power generation element; and In a thermoelectric generator for an internal combustion engine comprising a low temperature member that contacts the other surface of the thermoelectric generator,
A holding member that is disposed concentrically in the exhaust passage and holds the disposition position by pressing the thermoelectric power generation element against the surface of the exhaust passage;
The thermoelectric power generation element is disposed between the holding member and the low temperature member so that the thermoelectric power generation element can slide with respect to both the high temperature member and the low temperature member according to a deformation amount due to thermal expansion. And providing an elastic member that is biased between the high temperature member and the low temperature member ,
An exhaust purification catalyst is provided inside the high temperature member, and the exhaust purification catalyst carrier is a metal carrier in which a large number of wall surfaces formed therein are integrated by extrusion molding. A thermoelectric power generator for an internal combustion engine. The thermoelectric power generator for an internal combustion engine according to claim 1, wherein a base that constitutes a part of the high temperature member and contacts the one surface is provided on an outer peripheral surface of the high temperature member. The thermoelectric power generator for an internal combustion engine according to claim 2, wherein a surface of the pedestal that is in contact with the one surface is formed in a shape along the one surface. The thermoelectric generator for an internal combustion engine according to claim 3, wherein the pedestal is formed in a polygonal column shape. The thermoelectric power generator for an internal combustion engine according to any one of claims 1 to 4, wherein the high temperature member is formed of austenitic stainless steel. The low-temperature member is a cooling mechanism through which a cooling medium flows, and the flow direction of the cooling medium in the cooling mechanism is set in a direction from above to below the cooling mechanism.
The thermoelectric power generator for an internal combustion engine according to any one of claims 1 to 5. The flow direction of the cooling medium is set in the forward direction with respect to the flow direction of the exhaust gas in addition to the direction from the upper side to the lower side of the cooling mechanism.
The thermoelectric power generator for an internal combustion engine according to claim 6. At least one of the one surface and the other surface is covered with an amorphous carbon film
The thermoelectric power generator for an internal combustion engine according to any one of claims 1 to 7.

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